Polymer mechanochemistry focuses on molecular-level mechanochromism and chemical transformation under external mechanical inputs. This emerging tool has demonstrated powerful potentials for the development of next-generation mechanoresponsive materials and sensors. Near-infrared (NIR) luminescence plays a crucial role in biological applications such as bioimaging, clinical diagnostics, and anticounterfeiting because of its superior penetration depth and low phototoxicity. Developing mechanoresponisve NIR polymers, therefore, is essential to expand the application of mechanochemistry into biological systems. The major challenges in the design of NIR mechanophore (a molecular unit that is sensitive to mechanical force) include tedious multistep synthesis, reduced chemical stability, and hindered force transduction efficiency. Recently, we reported the first NIR-mechanophore with a fused oxazine-heptamethine cyanine (OHC) moiety. In this presentation, I will discuss the molecular design strategy of the NIR mechanophore and its mechanoresponisve performance under various mechanical modes and states, including solution, thin-film, and bulk states. DFT-based CoGEF (Constrained Geometries simulate External Force) simulation will also be discussed to reveal the mechano-activation mechanism. Polymer mechanochemistry is a powerful tool to showcase a  molecular design strategy in developing mechanoresponisve smart materials. Polymers with forced-induced NIR chromism will bridge the gap between conventional polymer mechanochemistry and advanced biological applications such as biomechanics and bioimaging.

Near-infrared mechanochromism in polymeric materials

ACS Spring 2022

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.